Even though the L71 received a higher power rating, actual performance between the L71 and L72 is very close. In fact, the L72 had the best magazine quarter-mile time, albeit not by much-12.8 seconds at 112 mph versus the L71's 12.9 seconds at 111 mph. The L72's four-barrel carburetor may have given it a slight quarter-mile performance advantage. Some drag racers claim that a four-barrel provides better power delivery than a triple carb set-up. Tri-power L71s operate on the primary center carburetor until you put your foot into it, then the two secondary carburetors, controlled by a mass-air vacuum signal from the center carb's venturi, open up for full power. Those progressive, vacuum-controlled secondary carbs may be a slight disadvantage in the quarter-mile, but when working properly make for a smooth power buildup.

Magazine performance numbers and chassis dyno figures mixed with a little Corvette history make a compelling argument that Chevrolet did have its horsepower ratings correct for early production L72s and the LS6, but in between, advertised L72 and L71 ratings were on the low side.

Magazine Quarter-Mile Times for L71 and L72 Corvettes
12.8 sec. @ 112 mph ('66 L72, Nov. 1965 Car and Driver)
12.9 sec. @ 111 mph ('67 L71, May 1967 Cars)
13.3 sec. @ 108 mph ('68 L71, May 1968 Hi-Performance Cars)
13.4 sec. @ 105 mph ('66 L72, March 1966 Motor Trend)
13.41 sec. @ 109.5 mph ('68 L71, June 1968 Car and Driver)
13.6 sec. @ 105 mph ('67 L89/L71, 1967 Car and Driver)
13.8 sec. @ 108 mph ('67 L71, May 1967 Hot Rod)
13.8 sec. @ 104 mph ('67 L71, April 1967 Motor Trend)
Average; 13.38 sec. @ 107.94 mph

Magazine Quarter-Mile Times for LS1 Corvettes
13.0 sec. @ 109.6 mph ('03 LS1 350hp convertible, 2003 Motor Trend)
13.2 sec. @ 109.3 mph ('99 LS1 345hp coupe, May 1998 Motor Trend)
13.2 sec. @ 109.3 mph ('99 LS1 345hp coupe, May 1998 Motor Trend)
13.3 sec. @ 106.8 mph ('97 LS1 345hp coupe, February 1997 Motor Trend)
13.3 sec. @ 108.6 mph ('99 LS1 345hp hardtop, September 1998 Motor Trend)
13.3 sec. @ 106.8 mph ('97 LS1 345hp coupe, February 1997 Motor Trend)
13.4 sec. @ 105.5 mph ('00 LS1 345hp convertible, February 2000 Motor Trend)
Average; 13.24 sec. @ 107.96

Average performance results show identical quarter-mile speeds for LS1 (107.96 mph) and L71 plus L72 Corvettes (107.94 mph).

BIG-BLOCK EQUIVALENTS
427-454
427 454 equivalent
L36, 390 hp LS5, 390 hp
L68, 400 hp LJ1, 400 hp*
L72, 425 or 450 hp LS6, 450 hp
L71, 435 hp LJ2, 460 hp
L88, 430 hp LS7, 465 hp
ZL1, 430 hp LT2, 465 hp